Finance Secretary Kate Forbes has said the SNP has not sufficiently laid the “groundwork” for independence.
Speaking during what is expected to be the final debate ahead of voting closing on Monday – hosted by Times Radio – Ms Forbes said the party has not worked in a “respectful fashion” with the other side of the independence debate.
The candidate has stressed the importance of change for the SNP, pitting herself against Health Secretary Humza Yousaf who has been considered by many as the continuity candidate in the race.
“Not that the case isn’t there, but because we haven’t been persuading, we haven’t been working in a respectful fashion with those who aren’t yet persuaded to persuade them.”
Ms Forbes went on to say “the root of all of this is trust”, adding that good governance would increase support for independence.
“Good governance is important for the sake of our NHS, but say for people, but it’s also political – govern well, and you earn the right to try and persuade the people,” she said.
“And the second thing I would say is around trust – earning confidence and the trust of the Scottish people is also important when it comes to making the case for independence.”
Mr Yousaf said it was a “personal disappointment” to him that support for independence had remained around the same level as was seen in the 2014 referendum.
“We just don’t have that consistent, sustained majority for independence,” he said.
He added that he “agreed with a lot of what Kate has said”, although it is not clear if his assessment around the case for independence was the same.
The two leading candidates also clashed on tax issues during the debate, with Mr Yousaf saying he would look to increase tax and potentially funnel that cash into a pay increase for social care staff.
The Health Secretary said he was in favour of “progressive taxation”, and he would “explore” the creation of a new tax band, similar to that proposed by the STUC.
“I think we are at our best when we’re radical,” he said.
Mr Yousaf added: “That additional revenue, additional income should be put into a number of things.
“For me, one of the areas I’m most attracted to is looking at how we can pay our adult social care workers more.”
In January, Mr Yousaf said increasing pay to £15 per hour would cost as much as £1 billion, so it is unclear how much of a rise the taxation would fund.
Ms Forbes said she was more in favour of growing the economy and getting people into more well paid jobs, which would expand the tax base.
“The risk is that if you overcomplicate income tax, which I think is the risk here… you could end up raising less, not more.”
But Mr Yousaf said it was not a case where you would have to do “one or the other”.
While Ash Regan, considered an outsider in the leadership race, said she would not look to change the tax system, but would hope to raise funding in other ways, pointing to potentially raising money from taking stakes in renewable energy projects.